[lxc-users] Better error logging when starting containers?

[Akshay Karle]

I agree with your comments and the fact that the team is busy working lxc
v2, but I wanted to get a sense of whether it was a problem everyone is
facing and that the lxc team are aware of. I didn't look into the codebase
for logging yet and I'm not a C programmer (anymore), but I would like to
give a shot at improving the logs and hence asked for your suggestions. I
will begin by looking at how we can improve error logging for lxc-start at
least and then look at the general lxc-* commands. Thanks for the comments
Bostjan, I'll keep that in mind when I look through the code.

Thanks for the tip on bumping the log level for ephemeral containers John!

On Mon, Feb 22, 2016 at 4:41 AM Bostjan Skufca <bostjan at a2o.si> wrote:

> Dear Akshay,
>
> I do agree with you and find this behaviour a bit annoying, yet I believe
> "patches welcome" response will follow shortly :)
>
> On a more serious note:
> As I skimmed over LXC code a while ago, it seems LXC bails out on first
> error that occurs. This means that implementing your suggestion would
> simply mean keeping last error stored somewhere and displaying it before
> exiting lxc-start itself.
>
> This would be solution for lxc-start, which you (and I) are probably the
> most interested in. Some more generic solution for all lxc-* tools should
> probably be more adequate, but that would need attention from one of the
> maintainers/core devs.
>
> b.
>
> On 22 February 2016 at 00:50, Akshay Karle <akshay.a.karle at gmail.com>
> wrote:
>
>> Hello lxc users,
>>
>> After having used lxc for a while now, I've realized that when the
>> container fails to start, it fails with a very generic message as follows:
>>
>> $ lxc-start -n test
>> lxc-start: lxc_start.c: main: 344 The container failed to start.
>> lxc-start: lxc_start.c: main: 346 To get more details, run the container
>> in foreground mode.
>> lxc-start: lxc_start.c: main: 348 Additional information can be obtained
>> by setting the --logfile and --logpriority options.
>>
>> And if you are using ephemeral containers, the error is even more generic
>> and with no way to increase the log level:
>>
>> $ lxc-start-ephemeral -n e1 -o test -d
>> setting rootfs to .%s. /home/vagrant/.local/share/lxc/e1/rootfs
>> The container 'e1' failed to start.
>>
>> I was wondering if someone felt the need of having a little more
>> meaningful error messages giving a summary of the error in the console
>> output. The container logfile does have way more descriptive error
>> messages, but since you don't directly have the errors in the console
>> output, you are forced to open the logfiles everytime something goes wrong.
>> Instead if you had an output that just included a few important error lines
>> from the logfile such as the following example:
>>
>> $ lxc-start -n test
>> lxc-start: lxc_start.c: main: 344 The container failed to start.
>> lxc_start - start.c:lxc_spawn:1031 - failed creating cgroups
>> lxc-start: lxc_start.c: main: 346 To get more details, run the container
>> in foreground mode.
>> lxc-start: lxc_start.c: main: 348 Additional information can be obtained
>> by setting the --logfile and --logpriority options.
>>
>> Do you think this would help? Although I have no idea if this is simple
>> to implement, I just wanted to get your ideas, suggestions and concerns (if
>> any) before attempting to figure out a solution.
>>
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>> lxc-users at lists.linuxcontainers.org
>> http://lists.linuxcontainers.org/listinfo/lxc-users
>>
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